Drill bit



Dec. 20, 1966 P. W. SCHUMACHER, JR

DRILL BI 'I' 2 Sheets-Sheet 1 Filed Jan. l5, 1964 DCC- 20, 1966 P. w. scHUMAc-HER, JR 3,292,719

DRILL BIT 2 sheets-sheet Filed Jan, l5, 1964 Percy VV. Jc/M/Wace/f, (/f'.

INVENTOR Bd `c JMJ-Nrj,

Arrow/VJ United States Patent O 3,292,719 DRILL BIT Percy W. Schumacher, Jr., Houston, Tex., assignor to Reed Roller Bit Company, Houston, Tex., a corporation of Texas Filed Jan. 15, 1964, Ser. No. 337,871 Claims. (Cl. 175-339) This invention relates generally to an earth boring drill of -the roller cutter type and more particularly to a drill for producing relatively large diameter bore holes.

In the drilling of earth bores for wells, shafts and the like, a bit head, having cutters mounted on the lower portion thereof, -is connected to the lower end of a drill stem which is rotated to cause the cutters to roll upon the bottom of `the bore hole being produced .to out or crush the formation being encountered. A drilling huid, which -may be a `gas or a liquid, is pumped downwardly through the drill stem and bit head and rises -in the space between the drill stem and the wall of the hole to the surface of the earth. Reverse rllow of the drilling uid may be employed by pumping the drilling uid downwardly about the drill stem and thence upwardly through the interior of the drill stem.

One of the most important desired 4functions of the drilling huid thus circulating is to remove quickly the cut or crushed particles of the formation from the bottom of the hole and from the roller cutters. This function is not always eciently performed, especially in the dr-illing of large diameter holes, because such bits may have widely spaced cutter assemblies and much space between the bit head and the bottom of the hole.

=If the cuttings are not quickly removed, they may be recut by the roller cutters, and the yformation particles may accumulate around the cutters and between the bit head and the bottom of -the hole, whereby the cutters may cease to rotate on their axes and may be worn by skidd-ing upon the hole bottom, thus reducing the useful life of the drill bit. Such formation clogging of the drill bit is commonly known as balling up. This invention has for one of its Ageneral objects the provision of a new and improved roller type drill bit having means arranged to cause the drilling fluid -to perform the desired function of quickly removing the formation particles from the bottom of the hole and from the areas about the roller cutters.

Another object is to provide a new and improved drill bit having widely spaced cutters arranged to effectively produce a relatively large diameter bore hole.

Another object is 'to provide a new and improved drill bit having skirts or means arranged between some of the roller cutters Ito channel or direct the drilling Huid closely along the hole bottom and about some of the Vroller cutters.

Other objects will become apparent from the following description and the accompanying drawings, in which:

FIGURE l is a bottom plan view of a drill embodying one form of the invention, showing the arrangement of the roller cutters and the skirts extending between some of the cutters.

FIGURE 2 is a sectional View taken along line 2 2 in FIGURE l.

FIGURE 3 is a fragmentary detail view taken along line 3-3 of FIGURE l.

FIGURE 4 is a bottom plan view of another embodiment of the invention.

FIGURE 5 is a detail view showing an alternate type of cutter assembly and another embodiment of the skirting means.

Referring to FIGURES 1, 2 and 3, a drill embodying the invention is shown generally at and includes a bit 3,292,719 Patented Dec. 20, 1966 ICC head 11. The bit head 1,1 comprises a lower plate |12 and an upper plate 13. An inner cylindrical spacer .14 and an outer cylindrical spacer |15 are disposed between the plates 12 and 13 and are welded or secured thereto in any other suitable manner. A portion of a drill stem is shown at 16, and a ange 17 is secured to the drill stern 16 by means of a weld 18. As shown, the diange 1-7 is connected to the plate .13 by Imeans of bolts 19. Central cutter assemblies 20 and 21 are welded or otherwise secured to the lower sur-face of the plate 12 of the bit head 11. Intermediate cutter assemblies 22 and outer cutter assemblies 23 are also attached to the bit head 1=1 in a similar manner. Each cutter assembly comprises a downwardly extending leg 24 having a downwardly and inwardly extending sha-ft (not shown) upon lwhich are mounted the roller cutters. The roller cutters m-ay halve conventional cutting teeth or other cutting elements and may be mounted on sui-table bearings as is well known in the art.

As may be seen in FIGURE 1, cutter assemblies 20 and 21 are arranged centrally to cut at and proximate the axis of the drill. The outer cutter assemblies 23 are disposed to cut in a path at and near the 'wall 25 of the bore hole. The cutter assemblies 22 are disposed to cut a path intenmediate the central cutters and the outer cutters whereby the entire bottom of the bore hole is drilled.

'Ihe drill stem I'16 has a passageway 26, and the bit head 11 has a passageway 27 therethrough in communication with the passageway 26 of the drill stem 116. A ygenerally cylindrical central skirt 28 is attached to the bit head 11 by means of a weld, and forms a continuation of the drilling iluid passageways 26 and 27. The skirt 2'8 extends downwardly in close proximity to the bottom of the hole, and the lower portion of the skirt may be scalloped or cut away las shown at 29 to Afit closely around portions of the cutter assemblies 20 and 21, 'which cutter assemblies extend radially inwardly of the skirt 28.

An outer skirt 30 Iis welded to the bit head 1111, and extends downwardly in close proximity to the bottom, and is arranged to substantially span the space between the outer cutter assemblies 23. It is cut away at its bottom edge as sho-wn at 31 for each outer cutter assembly 23 so that a portion of the outer cutter may extend radially outwardly thereof.

In operation, the drill stem '16 is rotated causing the bit lcutters to roll upon the botto-m to cut the formation being encountered. As shown in FIGURE 2, a drilling fluid, such as a liquid or a rgas, is circulated downwardly about the drill stem 16 and moves radially inwardly under the -outer skirt 30 and around the cutters 213 and around the cutters 20 and 21, under and lupwardly through the skirt 28 and the passageways 27 and 2610 the surface of the earth. Since an effective volume of the fuid thus eirculating is constrained to pass close to the -bottom of the hole and closely around some of the cutters, the cuttings will be eliiciently removed by the circulating fluid from the :bottom of the hole and from around such cutters.

If desired, the drilling fluid maybe circulated downwardly through the passageway 26 of the drill stem 16 and through the passageway 27 and central skirt 28, thence radially outwardly under the central skirt 28 and the outer skirt 30 and upwardly in the space between the stem 16 and the wall 25 of the bore hole to obtain a reverse but similar result to that just described as to cutting removal and cleaning of the cutters.

FIGURE 4 shows another embodiment of the drill bit of the invention and is similar in construction and operation to that just described, and comprises a bit head 11a having central cutter assemblies 32, intermediate cutter assemblies 33 and outer cutter assemblies 34 mounted on the bit head 11a. The drill employs the central skirt 28 to embrace the central cutters 32 in the manner just described. Skirts 35-are attached to andY extend downwardly from the bit head 11a, and substantially span the space between the outer cutters 34. The skirts 35 are arranged so that drilling fluid passageways 36 are formed between the outer surfaces of the skirts 35 and the wall 25 of the bore hole.

FIGURE is a fragmentary view showing an alternate construction having a cutter 37 mounted in a yoke-type cutter support 38. The cutter support 38 may be Welded to the bit head 11. The cutter 37 is supported on a shaft bearing'structure (not shown) in the well known manner. An outer skirt 39 is welded to the lbit head 11 and extends downwardly thereof. A skirt extension 40 is attached to the lower portion of skirt 39 by means of rivets 41 or the like. The skirt extension 40 may be made of a heavy rubber belting, or the like, and may extend downwardly from the skirt 39 in close proximity to the bottom of the hole.

It will be apparent from the foregoing that the invention will be found to be particularly useful in drill bits which drill bore holes 36 inches in diameter or larger, because relatively few cutters may be employed to drill the entire bore, and because of the provision of the skirts Which provide a drilling fluid circulation arrangement which will efficiently remove cuttings from the hole bottom and from the drill bit cutters.

This invention is not limited to the embodiments shown. Various changes within the scope of the following claims will occur to those skilled in the art.

What is claimed is:

1. In an earth lboring roller drill, a head adapted to be connected to the lower end of a hollow drill stem, said head having a central drilling uid passageway Vtherethrough in communication with the drill stem and the lower portion of said head, a plurality of central roller cutter assemblies secured to the lower portion of said head, and arranged to drill the formation at and proximate the axis of the drill, a plurality of outer roller cutter assemblies secured to the lower portion of said head, and arranged to drill an annularpath at and near the wall of the bore hole, intermediate roller cutter assemblies secured to the lower portion of said head and arranged to cut annular paths on the formation between said central and outer cutter assemblies whereby the entire bottom of the hole is drilled, a central skirt means attached to said head, and extending downwardly in close proximity to the bottom of the hole and forming a continuation of said central passageway to conduct drilling fluid toward or from the bottom of the hole, the said skirt being arranged to substantially span the space between the said central cutter assemblies, outer skirt means extending downwardly from said head in close proximity to the lbottom of the hole and disposed to substantially span the space between said outer cutter assemblies whereby circulating drilling uid is constrained to move radially near the bottom of the bore hole, under said skirts, and around some of the cutters to clean the same.

2. In an earth boring roller drill, a head adapted to be connected to the lower end of a hollow drill stern, said head having a central drilling fluid passageway therethrough in communication with the drill stern and the lower portion of said head, a plurality of central roller cutter assemblies secured to the lower portion of said head, and arranged to drill the formation at and proximate the axis of the drill, a plurality of outer roller cutter as-` semblies secured to the lower portion of saidhead, and

arranged to drill an annular path at and near the wall of` the bore hole, a central skirt means attached to said head@ and extending downwardly in close proximity to the bot-1 torn of the hole and forming a continuation ofsaid central,

passageway to conduct drilling uid toward or from the bottom of the hole, the said skirt being arranged to sub` ters to clean the same.

3. In an earth boring roller drill, a head adapted to be connected to the lower end of a hollow drill stem,'said` head having a drilling uid passageway therethrough in communication with the drill stern and the lower portion of said head, a plurality of central roller cutter assemblies secured to the lower portion of said head, and arranged to drill the formation at and proximate the axis of the drill, a plurality of outer roller cutter assemblies secured to the lower portion of said head, and arranged to drill an annular path at and near the wall of the bore hole, intermediate` roller cutter assemblies secured to the lower portion of said head and arranged to cut annular paths on the formation between said central and outer cutter assemblies whereby the entire bottom of the hole is drilled, a central skirt means attached to said head, and extending downwardly in close proximity to the bottom of the hole and forming a continuation of said passageway `to conduct drilling fluid toward or from the bottom of the hole, the said skirt being arranged to substantially span the space between Athe said central cutter assemblies, whereby circulating drilling uid is constrained to move radially near the bottom of the bore hole, under said;

skirt, and around the cutters to clean the same.

4. In an earth boring roller drill, a head adapted to be t connected to the lower end of a drill stem, said head having a drilling uid passageway therethrough, a plu rality of roller cutters mounted on the lower portion of said head, and arranged to drillthe entire bottom of a bore hole, skirt means secured to and extending down-` wardly from said head including a tiexible skirt extension in close proximity to the bottom of the hole, said skirt means substantially spanning the space between certain of the cutters, whereby drilling iluid may be circulated through said passageway and under said skirt means 5. In an earth boring rotary drill, a head, a plurality of roller cutters mounted on said head, a skirt on said head extending downwardly in close proximity to the bottom of a bore hole, and disposed between certain of said f cutters, the said skirt comprising a pliable material.

References Cited by the Examiner UNITED STATES PATENTS 839,837 l/l907 Guttzeit 175-355 1,582,332 4/1926 Brutus 175-339 3,100,544 8/1963 Overly 175-333 CHARLES E. OCONNELL, Primary Examiner. N. C. BYERS, Assistant Examiner. 

1. IN AN EARTH BORING ROLLER DRILL, A HEAD ADAPTED TO BE CONNECTED TO THE LOWER END OF A HOLLOW DRILL STEM, SAID HEAD HAVING A CENTRAL DRILLING FLUID PASSAGEWAY THERETHROUGH IN COMMUNICATION WITH THE DRILL STEM AND THE LOWER PORTION OF SAID HEAD, A PLURALITY OF CENTRAL ROLLER CUTTER ASSEMBLIES SECURED TO THE LOWER PORTION OF SAID HEAD, AND ARRANGED TO DRILL THE FORMATION AT AND PROXIMATE THE AXIS OF THE DRILL, A PLURALITY OF OUTER ROLLER CUTTER ASSEMBLIES SECURED TO THE LOWER PORTION OF SAID HEAD, AND ARRANGED TO DRILL AN ANNULAR PATH AT AND NEAR THE WALL OF THE BORE HOLE, INTERMEDIATE ROLLER CUTTER ASSEMBLIES SECURED TO THE LOWER PORTION OF SAID HEAD AND ARRANGED TO CUT ANNULAR PATHS ON THE FORMATION BETWEEN SAID CENTRAL AND OUTER CUTTER ASSEMBLIES WHEREBY THE ENTIRE BOTTOM OF THE HOLE IS DRILLED, A CENTRAL SKIRT MEANS ATTACHED TO SAID HEAD, AND EXTENDING DOWNWARDLY IN CLOSE PROXIMITY TO THE BOTTOM OF THE HOLE AND FORMING A CONTINUATION OF SAID CENTRAL PASSAGEWAY TO CONDUCT DRILLING FLUID TOWARD OR FROM THE BOTTOM OF THE HOLE, THE SAID SKIRT BEING ARRANGED TO SUBSTANTIALLY SPAN THE SPACE BETWEEN THE SAID 